We seek support to continue multidisciplinary studies of the development of the cerebral cortex. With the help of the initial Senator Javits Center we have established a team of investigators with expertise in molecular biology, immunocytochemistry, laser microscopy, electron microscopy, receptor pharmacology, computer imaging, and electrophysiology to join forces to explore five major themes: (1) Molecular mechanisms of neuronal migration to the neocortex; (2) Regulation of cell phenotype in developing neocortex; (3) Development of cortical circuitry in primate neocortex; (4) Ontogeny of major neurotransmitter receptors in the primate cerebral cortex; and (5) Development and modulation of synaptic plasticity studies performed during the previous cycle of the grant and represent some of the most advanced neurobiological approaches that can be applied to the complex development problems involved in cortical ontogeny. Cerebral cortex is the site of many mental and neurological dysfunctions whose cause can be traced to genetic and acquired developmental abnormalities. Prevention and healing of these disorders requires understanding molecular and cellular mechanisms involved in normal cortical development. Our experience is that a program project of this scope promotes communication between investigators with different backgrounds, fosters research collaboration, and enables comprehensive, multifaceted analyses that are either not possible or practical for individual investigators supported by separate research grants.